Remote control apparatus



@m 23, 1945. 1 E. HAYSLETT ET AL REMOTE CONTROL APPARATUS Filed Aug. 5, 1941 3 Sheets-Sheet l Oct, 23, 1945. 1 E. HAYSLETT ET A1. 2,387,444

REMOTE CONTROL APPARATUS Filed Aug. 5, 194]. 3 SheeiS-Shee'b 2 MMN\UHU Oct' 23, 1945- l.. E. HAYsLETT ET AL 2,387,444

REMOTE CONTROL APPARATUS Filed Aug. 5, 1941 3 Sheets-Sheet 3 nvvENToRs. HM/7K L. #fn/u frr.

BY figa 0550 NE. mf M Ml' REMOTE CONTROL APPARATUS Lamar E. Hayslett, borne, Snyder, N.

Kenmore, and Fred H. Os- Y., assignors t The Rudolph Wurlitzer Company, Cincinnati, Ohio, a corporation Appiication August 5, 1941, Serial No. 405,522

(Cl. 17V- 353) 3 Claims.

-itf'ention relates to a remote control appahich is particularly adapted to the selective of automatic record changing phonovephs but which is equally useful for the selece control of other mechanical or electrical ape invention in its preferred form includes a r adapted to generate electrical signals eiver adapted to receive said signals and selective operations in response tliere- '..bly the signals are transmitted over .e. li; es supplying power for operating the ismitteiy the receiver and the controlled maand said signals are in the form of a high cv carrier wave modified by low frequency r impulses. However, many features of the tion are applicable to other types of signal ssicn such as independent metallic circuits -or radio communication between the transmitter he receiver. One object or" the invention is to improve the and accuracy with which operating signals ivei.

object of the invention is to improve f' or the receiver to reject spurious signals d from outside sources.

sin features of the apparatus disclosed in resent application are shown and claimed in lng application of Charles J. Hull and i n. Gsborne, Serial No. 355,204, filed September 7.940, Patent No. 2,327,429 issued August 24, and co-pending application of Francis M. nidt and Gerald G. Smith, Serial No. 397,554, June ll, i9ll,`Patent No. 2,348,312 issued ther object of the invention is generally to "ove signal transmitting and receiving appaus of the type disclosed in said co-pending ilications i objects and features of the invention will `nod from the accompanying drawings lowing description and claims:

a diagram showing in conventional ...ation of the remote station, the reo a controlled machine in a form of the ion in which signals are transmitted over 'n s. Fig. 2 is a diagram of electrical con- :iid apparatus illustrating a preferred note control station. Fig. 3 is a similar -f .r illu trating a preferred form of receiving us. Fig. 4 is an elevational view of certain parts of the receiving apparatus of 5 is a similar view of the opposite side apparatus. Fig. 6 is a plan view of the transmitted, received and acted upon byv same. Fig. 7 is a diagram illustrating ai" native arrangement of a portion of the electri apparatus of Fig. 3.

The invention in the preferred form illustrated in the drawings is designed for use in a honi commercial establishment which is provided with the usual electrical wiring having suitable or -t sockets to which the controlled machine and the remote control apparatus may be co W c the usual socket plugs, For use in a comm application such as a restaurant, the cr' ordinarily be dependent upon the inse coin. Obviously for.` home use the coin may be omitted. of conductors l which may be considered as e distributory conductors of a commercial power company leading to the premises on whic. invention is to be used. Connected to the ductors l0 there is shown the usual local t former ll having a secondary winding conn ct to power mains l2 .supplying the individual cus-- tornei' of the power company. Suitable cutout switches and overload protection, not shown, may be assumed to be connected between the trans-- former ll and the mains i2. Appliance ou sockets i3 are connected to the mains l? usual manner and may be placed at any o. position on the premises. Adjacent any o the outlets i3 there may be transmitter lll having a cord and seche"J i6 which may be connected to the socket signal receiver l' having a cord and plug may be similarly connected to another cf the soci ets d3. Fig. 1 in the form of an automatic record c ing phonograph 2G connected to the signal re by a cord 2l. If desired, the receiver placed within the cabinet of the phonograp` Signal transmitter [la installed a sig For coin operation, the signal tran may be provided with a coin slotu E known form adapted to receive .co if denomination. Within the receiver tl e s vided a switch 23 which may be momen the buttons of which extend through the face of the transmitter |4 and are accessible to an operator. Each of said switches may correspond to a desired operation of the controlled machine and as many such switches as desired may be used. In Fig. 2 only four are shown. If a greater number is necessary, they are connected in a similar manner. The push buttons 24 are mechanically connected in a well known manner so as to be mutu- .ally exclusive-that is, when any one of said buttons is pressed to open its switch, the button is latched in position and any button or buttons previously pressed are released to normal position. The mechanism by which this mechanical connection is accomplished is well known in the art and need not be described in detail.

There is also provided a motor driven multipoint switch 25 having a series of contact points 26 and a contact segment 2l' connected by conductors 28 to the push button switches 24. Said switch has a contact finger 29 which is movable from an initial position shown in the drawings to engage successively the segment 2`| and the contact points 26, Other electrical apparatus within the transmitter |4 includes an electromagnetic relay 30 adapted when energized to close a pair of normally open switches 3| and 32.v A motor 34 is adapted to operate the multi-point switch 25 and to rotate a Contact disc 35, a cam 36 and a cam 3l. The mechanical connections of the motor to the switch 25, disc 35 and the cams 36 and 31 are indicated schematically in Fig. 2 by broken lines and it is to be understood that these connections are such that each of the driven parts makes one revolution in a definite period of time. The cam 36 operates a switch 33. The cam 37 operates a switch 4l). The contact disc 35 is engaged by contact ngers 38, 38A and 39 between which electrical contact is made through said disc at certain points in the cycle of operation. The contact disc 35, the cams 36 and 3i and the switch 25 are shown in Fig. 2 in an initial idle position. Each cycle of motor operation starts with the parts in this idle position and continues until all of said parts are simultaneously returned to said position.

There are also provided electron discharge tubes 4|, 42 and 43. Tube 4| is lshown as a standard .pentode tube and is used as a generator of radio frequency energy. Tube 42 is a twin triode tube.

necessary D. C. potential for the plate circuits of tubes 4| and 42. A condenser 53 connected between the cathode and ground serves to smooth out the D. C. voltage.

The cathodes of the several tubes may be heated by heating elements connected to suitable taps on the primary or secondary windings of the transformer 41 in a conventional manner.

The remaining electrical apparatus illustrated in Fig. l may best be described in connection with the circuits in which they are included.

In the operation of the transmitter, one of the push buttons 24 is first pressed to open its corresponding switch. Each of said push buttons corresponds to an operation of the controlled machine and in the case of a selective record changing phonograph, each of said buttons corresponds to one of the records carried in the magazine of said phonograph. When one of the buttons 24 has been pressed, a coin is deposited and switch 23 is momentarily closed to complete a circuit for the winding of relay 30 from the line conductor 44 through switch 23, relay 3D, ringer 38, disc 35 and nger 39 to line conductor 45. The consequent actuation of relay 39 closes switch 3| which is in parallel with switch 23 and thus retains the relay in energized condition after switch 23 has been opened.

The operation of relay 30 also closes switch 32 and completes a circuit through said switch to start the motor 34. The first movement of the motor vmoves the contact disc to bring iinger 38A into engagement therewith. The resulting electrical connection from nger 38A through disc 35 and iinger 39 to the line conductor 45 short circuits the switch 32. The motor thus continues to operate until disc 35 has made a complete revolution and a recess 54 in said disc reaches the ringer 38A and breaks the last men- 40 tioned electrical connection. This occurs when One of the triode elements is used as a radio frequency amplifier and modulator and the other as an audio frequency oscillator. Obviously, two standard `triode tubes could be used in place of the single tube 42.v Tube 43 is shown as a diode tube connected as a half wave rectier to supply the necessary D. C. plate voltages for tubes 4| and 42. In practice it is advantageous to' combine the elements of tubes 4| and 43 in a single tube but separate tubes are illustrated in the drawings for the sake of simplicity.

Power for operating the transmitter is supplied from the plug I6 to a pair of line conductors 44 and 45 in one of which there may be placed a cut-out switch 44A and in the'other an overload fuse 45A. A transformer 41 has its primary winding-connected to the line conductors 44 and 45 and its secondary winding arranged to supply current for the rectifier tube 43. One terminal of the secondary winding of transformer 4i is grounded and the opposite terminal is connected to the anode of the rectifier tube 43. The cathode 5| of said tube is connected to al distributory conductor 52 which is maintained' thereby at a suitable potential above ground and supplies the the parts have returned to their idle position and a complete cycle of motor operation is thus obtained even though' switch 32 is opened during the cycle.

At a convenient point in the cycle of motor operation an opening 55 in the contact disc 35 engages the finger 38 and breaks the circuit through the relay 30. Said relay thus returns to normal position with the switches 3| and 32 open.

By means of the apparatus just described, an extremely brief momentary operation of the switch 23 results in a complete cycle of motor operation. The retaining or stick circuit for the relay through switch 3| and the retaining circuit for the motor through ngers 38A and 39 insure positive operation of the cycl'e even though the closure of switch 23 is too-'brief in itself to give a positive initiation to the motor operation.

At the beginning of a cycle, the operation of the motor moves cam 36 to close switch 33 and said switch remains closed throughout the cycle of operation. The closing of switch 33 starts the operation of the radio frequency oscillator tube 4|. Said tube is provided with a conventional anode-cathode circuit leading from the D. C. distributory conductor 52, through inductance 5S and tuning condenser 51 in parallel to the anode 58 and thence through the cathode 59 and switch 33 to ground. The grid-cathode circuit leads from cathode 59 to control grid 60 through resistor 6| and the parallel path formed by inductance 62 and condenser 63. Inductance 56 and 32 are coupled to give the necessary feedback for oscillation and the frequency of oscillation is controlled by the tuning condenser 51. Preferably oscillations of the order of 250 kc. are used. Since switch 33 is included in the anode-cathode circuit, radio frequency energy is generated in the circuits of said tube only when switch 33 is closed.

The radio frequency energy generated in the tube 4| is amplified and power modulated by the tube 42 and associated circuits. In tube 42 the audio oscillator section consists of cathode 64, control grid 65 and anode 86. The radio frequency section of the tube consists of cathode 61, grid B8 and anode 69. 'The two cathodes 64 and 81 are connected together and are connected to ground through the lower half of a, variable inductance 10 which is thus common to the cathode circuits of both sections of the tube. A condenser 1| serves as a radio frequency by-pass for the cathodes The control grid 65 is connected to the cathodes through a resistor 12 and to the inductance 10 through a resistor 13, the switch 4D, the switch 25 and certain of the switches 24, depending upon the position of the nger 29. A condenser 14 is shunted across the inductance 10 to complete the audio frequency tuned circuit.'

The plate 66 is directly connected to the D, C. distributory conductor 52. The grid 68 is coupled to the grid of tube 4I through a condenser l and resistor 16. Inductance 11 serves as a radio frequency choke between grid 68 and the cathode circuits. Anode 89 is connected to the D. C. distributory conductor 52 through' condenser 18, variable condenser 19 and inductance 88 all connected in parallel and together forming a radio frequency tank.

in the electrical connections just described, the inductance and condenser 14 vform the tuned circuit of the audio frequency section of the tube 42. The grid B5 receives the necessary energy for oscillation from the tuned circuit only when switch 48 is closed and a circuit is complete from said switch through switch and one or more of the push button switches 24 to the inductance 10 and condenser 14. The lower portion of the inductance 18 also forms a part of the cathode circuit of the radio frequency section of the tube so that the potential of th'e cathode 61 is affected by the oscillating current in the inductance 10. Thus the inductance 10 serves the dual purpose of producing oscillation and controlling the potential of the cathode 61 to modulate the radio frequency energy.

During each cycle of motor operation, the cam 31 and switch 25 are rotated through a'complete revolution. The cam 31 is provided with a projecting portion 88 adapted to engage and close the vswitch 40 for an appreciable period of time at the start of motor operation. Thereafter said switch is engaged by a series of teeth 89 to produce a succession of much briefer momentary actuations of said switch. The operation of switch .48, so long as the circuit is complete through switch 25 and the push button switches 24, thus results in modulation of the radio frequency energy in the form of a single relatively long power impulse followed by a succession of much shorter impulses.

The switch 25 is operated by the motor 34 in timed relation with the operation of the impulse switch 40 and this relation is such that the finger 28 engages the contact segment 21 during the long impulse and the first of the shorter impulses produced by switch 40. The second of the shorter impulses occurs when the finger 28 is in engagement with the first of the contact points 26. Siniilarly, successive impulses occur while the contact finger is in engagement with successive contact points 26. The contact finger 28 is constantly in engagement with a contact ring 88 connected to the inductance 18 and condenser 14. The contact segment 21 is connected to the switch 40. Thus the modulating circuit is always complete during the long impulse and the first of the shorter impulses. Thereafter the movement of finger 28 introduces the switches 24 successively into the modulating circuit. When a switch 24 which has previously been opened is introduced into the circuit, said circuit is broken and no further power impulses can be produced even though switch 48 continues to operate. For example, if the first of the switches 24 has been selected, the circuit is broken when the finger 29 moves to the first of the contact points 26. The generated signal then consists only of the long impulse and a single shorter one. If the rst of the switches 24 is in normal position and the second of said switches has been opened, a second short impulse is added to the signal. 'Ihus the number of short impulses is determined by the selection of the proper switch 24. In the specific construction just described, the switch 25 and selector switches 24 operate upon the modulation circuit. While this is a preferred arrangement, it is obvious that this form of control may be applied to other circuits which control the transmission of the signals.

Radio frequency energy from tube 4I is fed to the grid. 68 through the condenser 15 and resistor 16 and is amplified, modulated and impressed upon the tank circuit 18-19-80 by the radio section of the tube 42. The inductance is coupled with an inductance 8l, connected in series with an inductance 82 and a condenser 83.' The inductances 8| and 82, and the condenser 83 form a link circuit in which currents induced by the coupling with inductance 8l may be tuned by the condenser 83 to eliminate harmonics. The inductance 82 is closely coupled with an inductance 84 and loosely coupled with an inductance 85, and

said coupling induces corresponding high frequency energy therein. One terminal of each of the inductances 84 and 85 is connected to the line conductor 44, and the opposite terminals of said inductances may be selectively connected to the line conductor 45 by a switch 86 connected to the last mentioned line conductor through a con=` denser 81.

By means of the connections just described, the amplified and modulated radio frequency output of tube 42 is impressed upon the line conductors 44 and 45 by either one of the inductances 84 and 85, the particular one of said inductances to be used being chosen by manual operation of the switch 86, and the choice depending upon the impedance of the external circuit between the remote station and the local station and consequent strength of signal required.

From the foregoing description it will be apparent that the transmitter generates and impresses upon the power lines a signal consisting of a high frequency carrier modulated by a single relatively long power impulse followed by a rapid succession of shorter impulses and that the number of shorter impulses in the series is determined by the particular push button switch 24 which has been selected.

controlled machine 20 is supplied from the plugl lil to a pair of power lines lll@ and i. A transformer |02 has its primary winding connected to the power lines |06 and lOl and has the terminals of its secondary winding connected to the anodes of a rectifier tube |03. The cathode f said tube is connected to a D. C. distributory conductor and the midpoint of the secondary winding of the transformer is connected to a conductor |07. The conductors |05 and lll'l are connected by an ex- .ternal load circuit consisting of resistors |06, |06

andy ills normally connected in series between said conductors. The rectifier tube |93 thus serves as a iull wave rectifier to maintain a suitable D. C. potential difference between conductors |05 and lill. One terminal of the resistance |68 is grounded as shown in Fig. 3 and the resistances mentioned are so chosen that conductor Ill'l carries a negative potential of approximately 95 volts and the conductor lil carries a suitable positive potential for the plate circuits of the several tubes used in the receiver.

The electrical apparatus of the receiver also includes a radio frequency transformer |63, a pentode tube l lll used for radio frequency amplification, a radio frequency transformer lll, a tube M2 having a diode rectifier section and a triode amplifier section used for audio frequency ampliiication, a similar tube H3 and a pentode tube l'lSA.. Other electrical elements shown in Fig. 3 will be described in connection with the circuits in which they are included.

The primary winding of the transformer 09 is connected to the line conductors i and lill through condensers l lil and l l5 adapted to transmit radio frequency energy but to block the usual cycle commercial current. Thus the modulated radio frequency signals generated in the transmitting apparatus are conducted from the transmitter lil through the line conductors l2 and line conductors |06 and lill to the transformer 4H59 and said signals induce corresponding currents in the secondary winding of said transformer. A tuning condenser i l@ is connected in parallel with the secondary windings of the transformer lli@ to complete resonant circuit which may be tuned to the radio frequency o the incoming signals. The resulting signal is impressed on the control grid ill of tube H6. rI'he cathode lid of tube im is connected to ground through a conventional biasing resistor H9 and condenser 2? and the anode |2l of said tube is connected to the positive D. C. distributcry conductor lii through a tuned circuit consisting of the primary winding of transformer ill and a tuning condenser 422. The connections lust described constitute a conventional stage of radio frequency amplilication by means of which the incoming signals are amplified and impressed upon the primary winding of transformer l l l.

The secondary winding of transformer iii is provided with a tuning condenser 23 in parallel therewith to complete a tuned secondary circuit, one terminal or which is connected to the anode 52d of the rectifier section of tube H2. The opposite terminal of said tuned circuit is connected to the cathode |25 of said tube through resistors ZG, lil and |28. The D. C. voltage produced in The control grid |33 of the amplier section of tube ||2 is connected through a coupling condenser |34 to a point in the rectifier circuit just described where suitable variations in voltage arey obtained for the operation of said amplifier section. Said grid is connected to ground through a conventional grid coupling resistor |3A. The cathode |35 is connected to cathode |25 and is biased to ground in a conventional manner. The anode |36 is connected to the D. C. distributory conductor |05 through a resistance |37. The con nections just described complete a conventional stage of audio frequency amplification as a result of which a pulsating current of audio frequency corresponding to the transmitted impulses is generated in the circuit of` anode |36.

The anode |36 is coupled through a series tuned circuit consisting of a condenser |38 and inductances |39 to a rectifier circuit including the rectier cathode |40, a variable inductance itl, parallel connected condenser |42, a resistance |63 and the anode |44. The condenser |42 and inductance lill form a parallel tuned circuit which together with the series tuned circuit |36-|39 passes the audio frequency signals of the desired frequency and rejects all others. As a result a rectified current iiows in said rectifier circuit during signal impulses and the direction of said current is such that the upper terminal of resistor M3 is at a lower potential than the lower terminal thereof when current is owing. Between irnpulses and when the apparatus is standing idle, no rectified current ows and both terminals of resistor M3 are at the same potential-i. e. the potential of the negative D. C. distributory conductor |81 to which the lower terminal is connected.

The cathode |435 of the triode section of tube IIS is connected to the lower terminal of resistance |63 and the control grid |416 is connected to the upper terminal. The anode |67 is connected to ground through a. resistance M8. Since the resistances |08, |06 and |05 in the external load circuit of the rectier |03 are proportioned' to maintain the potential of conductor |67 approximately volts below ground potential, the connection of anode lill to ground gives said anode a potential sufficiently above that of cathode M5 for operation of the triode section of the tube.

In the operation of the second section of tube H3, the cathode and control grid |66 are at the same potential as long as no signal impulses are received. The anode circuit therefore draws a steady direct current from the rectifier |03.

When a signal impulse is received the resulting current through resistor N3 depresses the potens tial of grid M5 to a point where cutol occurs and the anode current is thereby interrupted for the duration of the signal impulse. The output of tube i i3 therefore consists of a steady direct current interrupted during each signal impulse.

In the tube H3A. the cathode |69 is biased to ground through resistance |50, the control grid i5! is directly connected to the anode |131 and so carries substantially ground potential during signal impulses and considerably less than ground potential in the idle state of the apparatus when current hows in the circuit of anode lill and there is a corresponding voltage drop in resistor Hi8. The low grid voltage in the idle state biases the tube to cutoff, while the increase during signal impulses is sufficient to permit a strong plate current to ow between the anode 62 and the cathode m9. The output of tube is therefore the reverse of that of tube H3 isists of a series of current impulses cornding to the signal impulses received. The e of tube H3A is connected through the ci an eiectromagnet coil 153 to the posi- D. distributory conductor 105 and said ffnet coil may therefore be energized by the fic oi current in the anode circuit in response to the signal impulses.

order to prevent actuation of the magnet 153 i "7 transient impulses of brief duration, there is provided time delay means which initially limits spouse of the magnet to impulses of at least determined duration less than the duration the long impulse with which each signal series begun but greater than the duration of the shorter subsequent impulses and greater than the duration oi spurious impulses apt to be received on the power lines from external sources. When the relay i has once been actuated in response the longer impulse, the time delay device is .atically rendered inactive and remains intive until a predetermined time after the cesen a series of impulses. Thus the relay may respond to the briefer signal impulses they follow normally a longer impulse. time saving resulting from the use of relaely brief signal impulses is thereby realized ut danger that the apparatus may be im- 1 operated by brief impulses from an expreferred form of the apparatus shown d e drawings, the time delay device mentioned ioregoing paragraph consists of a coni connected at one side to the anode and control grid E61 and at the other side cted to ground through a normally closed A second condenser ISB of much capacity is permanently connected to und in parallel with condenser 1.54 and switch The changes in potential of the anode H1 u control grid ii must be accompanied by spending changes in the charges carried by condensers i and 156. The time required o charge both of said condensers when a signal e received is sufficiently great to prevent c, f :reaching an operative potenm unless the impulse persists for a predeterd ieriod of time. The capacities of the sers so chosen that this predetermined i ci is less than the duration of the long imwhich begins each signal series but is conably greater than the duration of the shorter pulses. As long as the condenser 154 remains cted, the magnet i53 cannot respond to the er signal impulses but may respond to the r initial impulse. When the switch 55 has opened, as hereinafter described, the conenser iii@ is disconnected from the circuit and c condenser i@ alone controls the" timing of spense. The capacity of condenser 156 is suftiy low to permit accurate response to the er signal impulses.

r operates a double throw switch Icy means oi which the resistance iii is disfrom the external load circuit of the r and the winding of a relay 158 is uted therefor in said circuit. The relay rates" the switch 155 to disconnect the .er i-'l and render the apparatus responto the shorter signal impulses. The relay is of the slow drop type in which the drop- Y it time is less than the normal interval bei signal impulses. The switch 155 thus reopen throughout a series of signal impulses and is closed only after the lapse of predetermined time after the last of such a series. Said predetermined time is determined'by the drop-out time of the relay 158.

The substitution of the relay coil 58 for the resistance 106 in the loadcircuit of the r ctiier 103 insures that the resistance characteristics and potential characteristics remain substan tially the same. This." is made possible by the fact that the resistance of the windings of relay 158 is made substantially the same as that of the resistance 106. Furthermore, condensers iii@ and 160 of relatively large capacity connected across said load circuit resist sudden changes in potential characteristics. When switch ld is operated by relay |58, a front contact of said switch connects a resistance 161 in parallel with the resistance 108. The resistance 16! provides an additional current path to carry the increased current in the lower portion of the load circuit caused by operation of the magnet |53 and thus insures that said operation does not materially disturb the voltage characteristics of said load circuit. The relay 158 also operates a double throw switch 162 which disconnects the resistance 104 from the rectifier load circuit and connects the winding of a slow drop magnet it in its place. The purpose of the operation of said magnet will be described hereinafter.

Briefly recapitulating the operation of the apparatus just described, the magnet i553 responds iirst to the long initial signal impulse and in so doing actuates magnet 58. Magnet 15e switch 165 to disconnect condenser iSd and i ne der the magnet 153 responsive to the shorter imn pulses. Magnet |58 also actuates magnet i613 through switch 162. During a series of impulses the magnet 153 is repeatedly actuated and magn nets 158 and 163 remain continuously in actuated position. At the end of a series of impulses, magn net 158 drops out and at a predetermined time thereafter, depending upon its drop-out time, magnet 163 returns to its normal position.

Referring now to Figs. 4, 5 and 6, there is shown therein mechanical apparatus controlled by the magnets 53 and 163. Said apparatus includes a stationary frame i6!!- in which there is mouned a rotatable shaft 165. Said shaft has secured thereto a ratchet wheel 166 and a pair of con tact fingers i6? and i68. The contact finger it? is adapted to engage contact points, itil mounted on an insulation plate ilii and the finger is adapted to engage a contact segment i'ii mounted on said plate. The fingers 161 and M38 are elecn trically connected to each other but suitably insulated from the shaft 165 and other parts oi' the apparatus. 'Ice magnet 1531is mounted on a core H2 suitably supported on the frame it@ and provided with an armature 13 mounted on. a rocking collar 114 which is freely carried on the shaft A65. The rocking collar VM is provided with an arm V15 carrying a pawl iid adapted to engage the teeth of the ratchet wheel idd. The rocking collar 1'14 is normally held in the position shown in the drawings by a tension spring and the pawl 176 is urged toward engagement with the ratchet 166 by a tension spring H8. 'in the position however, the spring ii'l holds the par/l 116 against a stop pin H9 and retains said pawl out of engagement with the ratchet. The rocking collar H4 is provided with an insulated pin ill adapted to engage and actuate the switch i5?.

In the operation of this portion oi the ratus each actuation of the magnet dra f the armature |13 toward said magnet and rocks the collar |19 on the shaft |65. At each such operation the pawl |16 engages the ratchet |66 and advances the saine a distance corresponding to one tooth of the ratchet. Each such advance also corresponds to the spacing of the contact points |69 so that the nger |61 is brought successively into engagement with said contact points.

The magnet |63 is provided with a core |8| mounted on the frame |66 and provided with a number of copper slugs |82 to provide the necessary slow drop action. Said magnet has an armature |83 normally held against a stop |86 by a tension spring |85. Said armature carries a resilient finger |86 engaging a pin |81 carried by a pawl |88 which is pivotally mounted on the frame |64 by means of a pivot screw |89. The armature |83 also carries a rigid iinger |90 adapted to engage the undersurface of the pin |81.

In the operation of the magnet |63 the finger |86 resiliently presses the pawl |88 against the ratchet |66 and prevents counterclockwise movement of said ratchet, referring to Fig 5, while permitting clockwise movement of said ratchet by operation o f the magnet |53. When the magnet |63 is deenergized at thefend of a series of signal impulses, the nger |99 positively lifts the pawl |88 clear of the ratchet wheel |66 and permits said ratchet wheel to be returned to normal position by a' tension spring |9| anchored at one end of the frame |66 and at the other end anchored to the shaft 65.

Referring again to Fig. 3, there is shown therein the controlled machine 20 in diagrammatic form. Said machine may be an automatic phonograph of the type disclosed in Wilcox Patent No. 2,002,236`in which there is provided electromagnetic control of the selection of phonograph records. Said machine has a series of electromagnets |92 which may correspond to the magnets |15 of the Wilcox patent, each of which controls the selection of a certain phonograph record. There is also provided a magnet |93 which may be considered as corresponding to the magnet |56 of the Wilcox patent and which initiates an operation of the machine. Speaking more generally, the magnets |92 and |93 may be considered as representing any suitable electrical elements for the control of mechanical or electrical apparatus. Each of the magnets |92 is connected to one of the contact points |69 and each has its opposite terminal connected to the power line |08, The contact segment |1| and the magnet |93 are connected to one terminal of a normally open switch |99 operated by the magnet |63. The opposite terminal of said switch is connected through a normally closed switch |95 to the power line The switch |95 is operated by the relay |58.

In the operation of the parts just described, the magnet |53 is actuated in response to the initial long signal impulse and the magnets |58 and |63 are then actuated in sequence. Switch |95 is opened before switch |96 is closed so no electrical connection is made through said switches. The actuation of magnet |63 presses the pawl |88 into engagement with the ratchet wheel |66 and prevents reverse movement of the selector finger |61 during the intermittent operation of magnet |53. Successive actuations of magnet |53 in response to a given number of the shorter signal impulses advances the selector nger |61 to one of the contact fingers |69 depending upon the number of shorter impulses irl the series. Said selector thus conditions the circuit of the corresponding magnet |92 for Isubsequent operation. At the end of a series of signal impulses, magnet |58 drops out and closes switch |95. Due to the delayed action of magnet |63, switch |94 remains closed for an appreciable time thereafter. During this period circuits are completed for the selected magnet |92 and for the magnet |93. The correspondingphonograph record is thereby selected and the phono-v graph is set into operation. When the magnet |63 finally drops out, the circuits just mentioned are broken and the pawl |88 is released to permit the spring |9| to return the selector |61 to initial position. Said initial position is determined by a rigid finger |96 secured to the shaft |65 and engaging a stationary stop pin |91.

By means of the apparatus just described the time of transmission of a series of signal impulses has been greatly reduced. The shorter signal impulses may be transmittedat the rate of 20 per second and the longer initial impulse may be as short as a sixth of a second. When a selection of 24 operations is provided, the entire cycle of transmission may be run through in less than two seconds. This speed of operation is of particular importance where a number of remote stations are used to control a single machine since it reduces to a negligible factor the chance of simultaneous operation of two transmitters.

The invention has been described in one of its preferred forms, the. details of which may be varied by those skilled in the art without departing from the scope of the invention as defined in the appended claims.

For example, different forms of time delay devices may be used to prevent operation of relay |53 in response to short impulses not preceded by the initial long impulse, and one such alternative arrangement is shown in Fig. '7. In that figure there is shown a portion of the apparatus of Fig. 3 and parts common to both arrangements are indicated by similar reference numbers. The time delay device consists of an in.- ductance 256 connected between the anode |91 of tube ||3 and the resistor |68. Electrical energy is stored in said inductance at each signal impulse and the connection is such that operating potential is not built up on grid |5| until a predetermined quantity of such ener'gy has been stored. A switch 255, operated by the relay |58 when relay |53 has once been energized, is connected to short-circuit the inductance 254| and y thus remove said inductance from effective connection to the circuit. 'Thereafter the relay |53 may respond to the shorter impulses.

The invention claimed is:

1. In an impulse receiver for a remote control system, the sub-combination of an electrical unit responsive to signal impulses received by said receiver, a time delay device associated therewith and normally limiting response of said electrical unit to impulses of greater than a predetermined duration, switching means controlled by actuation of said electrical unit and adapted to render said time delay device inactive, whereby said electrical unit becomes responsive to impulses of shorter duration, and other time delay apparatus actuated by response of said electrical unit to the shorter impulses and associated with said switching means to delay return thereof to initial position for a predetermined period after cash such actuation, whereby said rst mentioned time delay device remains inactive through a series of the shorter impulses following the initial long impulse by an interval less than said predetermined period and occurring at intervals less than Said predetermined period.

2. In an impulse receiver for a remote control system, the sub-combination of a relay, electrical circuits adapted to operate said relay in response to signal impulses received by said receiver, a time delay device associated with said circuits and normally limiting response of said relay to impulses of greater' than a predetermined duration, and a slow drop relay actuated by operation of said first relay and controlling the operation of said time delay device to render the same inactive, whereby said rst named relay may respond to an initial impulse of greater than said predetermined duration and may then respond to a series of shorter impulses occurring at intervals not greater than the drop-out time of said slow drop relay and following the initial impulse( at an interval not greater than said drop out time.

k3. In an impulse receiver for a remote control system, the sub-combination of a relay, electrical circuits adapted to operate said relay in response to signal impulses received by said receiver, a condenser associated with said circuits and normlly arranged to be charged at each signal impulse and to delay operation of said relay while being chargedy whereby said relay is normally unresponsive to an impulse of less than a predetermined duration, a slow drop relay actuated by operation of said rst named relay, and switching means connected to said condenser and controlled by operation of said slow drop relay to disconnect said condenser from said circuits when said slow drop relay is energized, whereby said rst named relay then becomes responsive to a series of shorter impulses occurring at intervals less than the drop-out time of said slow drop relay.

LAMAR E. HAYSLETI. FRED Hx OSBORNE. 

